This invention pertains to the art of power distribution and in particular to a power distribution cabinet which carries electric/electronic devices. The invention finds particular application in connection with modularized power distribution systems in the communication industry. It will be appreciated, however, that the invention has broader applications and may be advantageously employed in other environments and applications which impose access and wiring constraints in modularized distribution systems.
Distribution cabinets are in wide spread use in a variety of industries. Within the communication industry a variety of cabinets having different characteristics are used. Some cabinets are constructed to have doors and locks on an outer surface such that access can be limited to appropriate personnel. Other cabinets include front panels which allow a visual inspection of the components operating within a cabinet while denying access to the devices.
Still further, cabinets such as the battery distribution cabinet 10 of FIG. 1 have been constructed to allow access to the front of a device in the cabinet but limits access to the interior. Distribution cabinet 10 has been constructed for branch loading systems that can be configured for .+-.24 volt, 48 volt or 130 volt power systems with up to 600 amp capacities. The cabinet of FIG. 1 is designed to accept fuse panels 12 and circuit breaker panels 14, and is a rear access cabinet designed to allow for either one of top or bottom feeding of external power cables. The construction of distribution cabinet 10, is reviewed in greater detail in connection with FIGS. 2-5b and the following discussion.
FIG. 2 is a side view of cabinet 10. As shown by this view, fuse panels 12 and circuit breaker panels 14 are inserted through a front cover panel 16 and thereafter connected to bus bars 18, including connections 18a. The connections to bus bars 18 allows for the distribution of power throughout the cabinet. As further illustrated in FIG. 2, when it is desired to access any one of fuse panels 12 or circuit breaker panels 14 it is not possible to gain such access through the front of cabinet 10. Rather, the appropriate manner to access the internal area of cabinet 10 is through removal of rear cover panel 20. Though not shown in detail in this figure, rear cover panel 20 is connected to the cabinet through a variety of interconnection devices such as screws, bolts, clips or other known removable connection devices.
Removal of rear cover panel 20 allows access to the interior of cabinet 10. This is more clearly shown in FIG. 3 which illustrates a rear view of cabinet 10 with rear cover panel 20 removed. At this point if it is necessary to remove one of fuse panel 12 or circuit breaker panel 14 a technician may disconnect the required wires, bolts, screws, clips, etc. holding the particular panel in position. When the connections in the rear of the panel are disconnected, the panel or individual fuses or circuit breaker can then be removed. In some cabinets it may also be necessary to remove connection devices in the front face of cabinet 10, such as screws 24 shown in FIG. 1.
It is also noted that internal connection between circuit breakers and/or fuses of fuse panels 12, and circuit breaker panels 14 are wired through internal wires 22, and the external power is distributed through the cabinet by power cables 23. It is to be noted that the cabinet of FIGS. 1-3 is a bottom feed, wherein external cabling carrying power to the cabinet provides the power through the bottom of the cabinet, not shown.
Various feeding arrangements are shown with more particularity in FIGS. 4a-4b and 5a-5b, as will be discussed below. The internal wires 22 and cables 23 may each be bundled together at convenient locations and tied to internal areas of the cabinet at tie areas, typically these areas tie are integral with side cover panels 21a, 21b, to maintain the wiring in a secure position and to allow for an orderly organization of complicated wiring interconnections. The tieing of the wires is accomplished at convenient locations within the cabinet structure itself.
Returning attention to FIG. 2, this figure illustrates that if someone was attempting to access the interior of cabinet 10 through front cover panel 16 it would be necessary to substantially disassemble the cabinet. Particularly, as detailed in FIG. 1, fuse panels 12, and circuit breaker panels 14 are secured to front cover panel 16 through a connection arrangement such as with screws or bolts 24. However, even if these bolts or screws are removed, as can be seen in FIG. 2, since bus bars 18 are connected to panels 12 and 14 it would not be possible to remove the panels through the front face of front cover panel 16 as bus bars 18 would block such removal. For example, it would not be possible for a technician to reach in through the front panel in order to gain access to a location where the bus bars 18 are connected to the elements of fuse panels 12, and circuit breaker panels 14.
Typically, in such a cabinet, fuse the panels 12, and circuit breaker panels 14 are interconnected to the front cover panel 16. Therefore, if one were to attempt to gain access to the interior of cabinet 10 through the front of the cabinet of FIGS. 1-3, it would be necessary to substantially disassemble the cabinet which could require shutting down the entire power system. Also, though not shown with particularity in this view, cabinets will also use mounting trays, to which the panels are either mounted to or held on. Such trays are typically connected directly to the front panel. These arrangements create an undesirable situation, as technicians wish to be able to remove either individual fuses, circuit breakers or the panels of circuit breakers and fuses, 12, 14 while the remainder of the equipment within cabinet 10 are active. This cannot be accomplished through the front panel 16 of cabinet 10. Therefore, the typical manner of gaining access to the interior of cabinet 10 is through removal of rear cover panel 20 which has no such impediments.
Applicants note that FIG. 2 may appear to imply that there is a side access capability for cabinet 10. Specifically, it might appear from this view that a technician is able to remove a side panel of cabinet 10 and gain access to the interior of cabinet 10, since the main inhibiting elements from such an access are only connection bars 19. However, it is noted that this view of FIG. 2 is prior to any wiring or cabling required within the cabinet. FIG. 3 shows such wiring 22 and cabling 23. As FIG. 3 illustrates, internal wires 22 are arranged in bundles and tied to tie points associated with side cover panel 21a. Similarly, cables 23 which run along a side of cabinet 10 are tied at a location integral to side panel 21b. Therefore, when the cabinet is constructed, it is typically not possible to simply remove the side panel, since the tie points are connected to the side panels. In order to remove the tie points, it would be necessary to enter the cabinet from the rear and detach the tie points. Thus, again, entry into the interior of the cabinet is accomplished by rear access.
It is also noted that in addition to fuse panels 12 and circuit breaker panels 14, cabinet 10 also includes a metering panel 25, which generates analog and/or digital read outs which provide information as to the internal status of the devices within the cabinet. It is to be appreciated the metering panel may also deliver such information through auditory signals.
FIGS. 4a-5b illustrate different power feed arrangements for cabinet 10. FIG. 4a details a single load top feed arrangement wherein external power connections 26 feed the load of cabinet 10, thereby supplying power to the various panels. FIG. 4b illustrates the powering of cabinet 10 with a single load bottom feed arrangement, wherein the load is fed with external cables through the bottom of the cabinet, and where the cabinet in this arrangement further includes ground return 27. FIG. 5a is a dual load top feed arrangement wherein loads A and B are fed through external cable connections. FIG. 5b shows a typical dual load with bottom feed arrangement having loads A and B fed by external cable connections 28a and 28b and further including ground load returns 29a and 29b, for loads A and B, respectively.
In large distribution cabinets, the internal wiring may have a high degree of complexity, with numerous individual interconnections. Therefore, for organizational purposes, when constructing the cabinets, tie-points are used so that wires in a certain areas are bundled together and tied to a post or other structure included within the cabinet. This tieing of wires maintains order in the cabinet, thereby assisting in the construction of the cabinet and also allowing a technician to identify interconnections with greater ease.
As previously noted, the above described cabinet is commonly known as a rear access cabinet. If it is desired by a user to remove a particular panel for repair, replacement, or to otherwise service the panel, it is necessary to remove the rear cover panel 20 as shown in FIGS. 2 and 3, which allows access to the interior of the cabinet.
In this type of cabinet, it is not possible, however, to effectively obtain access from the front or sides of the cabinet. Particularly, as previously discussed, in constructing the cabinet, the configuration of the cover panels, fuse/circuit breaker panels and bus bar configurations and internal wiring/cabling do not allow detaching of front cover panel 16 or side cover panels 21a, 21b to gain direct access to the interior through the front or sides of the cabinet.
As an alternative to rear access cabinets, front access cabinets have also been configured. In such cabinets the configuration allows removal of the front panel to gain access to the interior of the cabinet. Alternatively, the panels may be detached from the cabinet and pulled out or otherwise accessed through the front panel.
Therefore, in a front access cabinet the front panel can be removed to access the interior of the cabinet or the panel, i.e. device itself is removed. However, in this situation rear access is not available, since structures holding the panels (e.g. fuse or circuit breaker points) or other elements of the cabinet, such as the bus bars, mounting trays, etc. are connected to the back panel.
In existing distribution cabinets when wires are tied on a structure included within the cabinet, it is a requirement of various safety agencies to insulate the tie areas, when these tie areas have edges of a predetermined angle. Particularly, the concern is that sharp angled metal, which is commonly used in distribution cabinets, can cut the wires which are being tied thereto.
It is also typical in existing distribution cabinets that the fuse, circuit breaker or other device panels are not physically or electrically segregated. This type of arrangement means that only a power source of a single value is provided to a cabinet.
Due to the above construction, it is necessary that the servicing, replacement or inspection of the device panels occur only through either one of a front side in a front access cabinet or a rear side in a rear access cabinet. Thus, while existing cabinets may be either front access or rear access cabinets, a single cabinet which allows both front and rear access does not exist.
Also, existing cabinets do not provide predefined tie point positions to ensure consistent repetitive location of the tie points. Further, in cabinets where the tie-points have sharp edges, another step in the building process is needed for insulating the tie point, as well as the additional cost for the insulation.
Additionally, the device panels are not segregated physically or electrically from each other thereby requiring the input power to be of a single value and also requiring a limited amount of panels which may be fed from a same source.
Therefore, it has been deemed desirable to construct a cabinet which allows for front, rear and side access of modules being carried in distribution cabinet and for such a cabinet which has defined passages for inner-cabinet wiring/cabling.
It has also been determined desirable to provide tie point areas which are integrated into a mounting of unit such that construction of the cabinet is simplified, thereby increasing the efficiency of production. This also eliminates the need for insulating at the tie points.
It has also been deemed desirable to form a cabinet in a single unit having two sides, i.e. a front and back side each having power termination protection or current protection modules inserted therein.
Still further, the cabinet should be constructed to receive modules which allow for physical and electrical segregation from each other, thereby allowing dual power sourcing as well as increasing the number of elements which may be fed from a same source. The cabinet should also allow for the monitoring of current for each module.